The invention relates to a throttle device for varying the pressure of a fluid in a plurality of parallel outlets. More particularly, the invention relates to a throttle device or a variable throttle comprising a fluid collector comprising an inlet for the fluid and a plurality of outlets for the fluid. Furthermore, the throttle device comprises a control element disposed so as to be movable, at least in part, in the internal chamber of the fluid collector. Furthermore, the control element comprises a plurality of orifices, and the orifices in the control element and the outlets on the fluid collector are configured and positioned such that the cross-section of a plurality of fluid communication routes between the internal chamber of the fluid collector and a plurality of outlets on the fluid collector can be varied by means of a relative movement of the control element in relation to the fluid collector.
Fluid collectors comprising such throttle devices are used in steam generators. They are suitable for steam generators comprising gravity circulation boilers or forced circulation boilers.
Throttle devices are known that are disposed in pipes of pipe registers in order to adjust the throughput volumes of a fluid flowing into the individual pipes under various flow conditions. However, one such throttle device must be provided for each pipe. Additional devices have been developed for controlling the throughput volumes in a plurality of pipes at one and the same time.
However, it must also be pointed out that undesirable instabilities and pressure losses can occur in such throttle devices comprising a plurality of supply lines. The device disclosed in DE 1 150 687 counteracts this problem and ensures that the inlet cross-sections of the pipe unions are unthrottled at normal loads and throttled during low-load operation.
The device disclosed in DE 1 150 687 comprises a fluid collector or a distributor container comprising an inlet for a working medium and parallel outlets disposed on the fluid collector in the form of connection unions or pipe nipples. Present in the fluid collector is a control bar or a filler element comprising inflow orifices assigned to the pipe unions. All of the inflow orifices can be opened or reduced in size as a function of the load with the aid of the control bar in the fluid collector. Since only one inflow orifice can be disposed on each side of the control bar, the device disclosed in DE 1 150 687 is able to throttle the throughput volume for each nozzle located in two parallel rows of connection unions at one and the same time individually, that is to say, without there being an unthrottled flow between the unions, and also to ensure a uniform throughput volume in the throttled state in this manner.
The device disclosed in DE 1 150 687 is therefore particularly suitable for the supply of throughput volumes to radiant heating surfaces in forced circulation boilers comprising only two parallel rows of pipes at any one time. However, if a greater number of parallel pipes is required, then a plurality of these devices must be arranged parallel to each other in order to achieve the desired depth and number of pipe rows.
The problem underlying the invention is therefore, when using known throttle devices, to control a plurality of throttle devices arranged parallel to each other in order to achieve a desired uniform throughput volume for a desired plurality of pipes.